Microporous Functionalized Triazine-Based Polyimides with High CO2 Capture Capacity

Porous organic polymers with polar surfaces are promising materials for capture and storage applications for carbon dioxide. Here, we present the synthesis and characterization of seven triazine-based porous polyimide (TPI) polymer networks and evaluate their applicability as CO2 sorbent materials. The TPIs were synthesized in good yields by a condensation reaction of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (TAPT) and the respective dianhydride building blocks in m-cresol. The resulting TPI polymer networks exhibited high chemical and thermal stability under air (up to 450 °C). Argon sorption isotherms demonstrated that specific BET equivalent surface areas up to 809 m2 g–1 (TPI-1) were reached. The characterization of the pore structure revealed mainly micropores with pore diameters ranging from 0.4 to 3 nm. The highest uptake values for CO2 (2.45 mmol g–1) were observed for TPI-1 and TPI-2 at 273 K and 1 bar. The highest binding selectivity (56) for CO2 over N2 at 298 K was observed for TPI-7. The high degree of functionalization led to comparatively high CO2 adsorption heats for TPI polymer networks between 29 kJ mol–1 (TPI-6) and 34 kJ mol–1 (TPI-1). As a result, the TPI networks showed high CO2 uptakes relative to their moderate BET equivalent surface areas. In combination with a facile modular synthesis procedure, a high chemical and thermal stability, and the tunability of the CO2/N2 binding selectivities, TPIs might be classified as promising materials for CO2 storage and separation applications.